Camper unit lifting device

ABSTRACT

Lifting device, operable by one operator, for lifting camper units on and off trucks. Hydraulic equalizer supplies equal volume flows of fluid to hydraulic jacks of jacking devices which carry camper unit. Jacks are straddled by telescoping guides to reduce bending moments on jacks. Jacking devices are canted inwards from bases of jacking devices, increasing stability of camper unit when carried on jacking devices. Equalizer ensures equal extension of jacks, reducing tendency of camper unit to topple.

United States Patent Kowalski [451 Oct. 10, 1972 CAMPER UNIT LIFTING DEVICE 3,567,271 3/1971 Gostomski ..254/45 X Primary Examiner-Othell M. Simpson Attomey-Lyle G. Trorey [57] ABSTRACT Lifting device, operable by one operator, for lifting camper units on and off trucks. Hydraulic equalizer supplies equal volume flows of fluid to hydraulic jacks of jacking devices which carry camper unit. Jacks are straddled by telescoping guides to reduce bending moments on jacks. Jacking devices are canted inwards from bases of jacking devices, increasing stability of camper unit when carried on jacking devices. Equalizer ensures equal extension of jacks, reducing tendency of camper unit to topple.

11 Claims, 6 Drawing Figures CAMPER UNIT LIFTING DEVICE BACKGROUND OF THE INVENTION 1 Field of the Invention The invention relates to a device for lifting camper units onto and off beds of trucks.

2. Prior Art Camper units, adapted to be transported on a bed of a truck, have been known for a long time. Many devices have been developed to lift camper units, the devices falling into two main catagories, namely mechanical jacks using screw threads, ratchet, or rack and pinion devices, and hydraulic devices using hydraulic cylinders as jacks. Both types of devices have a common disadvantage such that usually two people are required to raise the camper, one person working the lifting device on each side of the truck. To reduce a tendency of the camper unit to topple due to listing, i.e., leaning to one side, both sides are raised equally, a third person usually being required to check that the camper units is raised in a level manner.

When hydraulic jacks are used, often there is no provision to reduce bending loads being applied to the ram and cylinder, often causing leakage past the piston with a corresponding tendency for the ram to retract slowly into the cylinder. Also, due to variations in hydraulic jacks, when two jacks are fed from a common pressurized hydraulic fluid source, it is unlikely that both jacks extend at the same rate due to variations in the sealing and friction between the piston and the cylinder. Thus, although both cylinders are fed from a common pump there is a tendency for a camper to lean to one side during raising with a risk of toppling.

When the camper unit is lifted clear of the truck it is supported solely on the lifting devices until more suitable supports are fitted underneath the camper. As the lifting devices are in generally parallel planes, if a sufficiently strong sideways force were applied to the camper unit, the camper unit would topple, because there is little tendency for the camper to return to its original position. Thus a camper unit supported solely on prior art lifting devices tends to be an unstable system.

SUMMARY OF THE INVENTION The invention reduces difficulties above by providing a lifting device which ensures that the camper unit is raised generally evenly at each side, and also reduces chances of bending loads being applied to jacks of the lifting devices.

The lifting device of the invention includes two jacking devices coupled to a hydraulic unit having a hydraulic equalizer, the unit supplying equal volume flows of hydraulic fluid to hydraulic jacks of each jacking device. The jacking devices have camper unit engaging means spaced from support means which support the jacking device on the ground, the space between the means above being varied by an extensible and retractable means. Guiding means are provided to maintain the engaging and supporting means parallel during extension and retraction and canting means tilt the jacking devices at a small angle to the vertical to increase stability of the camper unit when supported solely on the jacking devices.

One embodiment of the jacking devices of the inven tion includes a cradle to engage the camper unit and a base to support the jacking device on the ground and resist sinking into the ground, a telescoping steady being provided at each end of the jacking device to maintain the cradle and base substantially parallel during extension and retraction. A hydraulic jack, hinged to the engaging and support means, is provided between the telescoping devices to extend and retract the jacking device, the jack being connected to the hydraulic unit. The base is provided with out-rigger braces which cant the jacking devices inwards at a small angle to the vertical, such canting being obtained by extension of a bolt provided at an outer end of the brace.

A detailed description following, related to drawings, gives exemplification of apparatus and method according to the invention which, however, is capable of expression in method and means other than those particularly described and illustrated.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a camper unit on a truck, a camper unit lifting device according to the invention shown in a position for lifting the camper unit,

FIG. 2 is a front elevation of the truck and the camper unit of FIG. 1,

FIG. 3 is a fragmented front elevation of the camper unit lifting device, with portions broken away to show interior construction,

FIG. 4 is a simplified section on line 4-4 of FIG. 3,

FIG. 5 is a schematic of a hydraulic unit used with the device of the invention,

FIG. 6 is a diagram showing camper unit tilting.

DETAILED DISCLOSURE FIGS. 1 and 2 A camper unit 10, is shown supported on a bed 11 (broken outline) of a truck 12. The camper unit has stepped sides having comer edges 13 and 14, and the truck has parallel side panels, one only shown in FIG. 1,

having a top edge 15 spaced from the lower corner edge 13.

A jacking device 17 is provided on each side of the I truck, that is two similar jacking devices 17 are required to raise the camper unit. Each jacking device is spaced symmetrically about an approximate balance point 16, the balance point being generally marked on both side walls of the camper unit. Hydraulic hoses 18 and 19 extend from each jacking device and are coupled to a hydraulic unit 20, to be explained with reference to FIG. 5, the two jacking devices, the hoses and the hydraulic unit forming the camper unit lifting device of the invention.

FIGS. 3 and 4 With reference to FIG. 3, the jacking device 17 has a cradle 26 at an upper end, and a base 27 at a lower end. The cradle is an engaging means for the camper unit and the base is adapted to lie on the ground and serve as a support means for the jacking device, the support means having a relatively large bearing area to resist sinking, both the cradle and base being horizontally disposed lengths of angle iron.

Vertical telescoping steadies 29 and 31 are provided at outer ends of the lifting device and extend vertically between the cradle and the base as shown. The steady 29 has an outer tube 33 with an upper end 34 secured to the cradle 26, and an open lower end 35. An inner tube 37 is a sliding fit within the tube 33 and has a lower end 39 secured to the base 27 and an upper end 38. The inner tube 37 extends upwards within the outer tube, the two tubes overlapping for an overlap length designated 41, clearance between the inner tube and the bore of the outer tube being such that the two tubes are maintained substantially aligned with each other and are free to slide axially relative to each other. The open end 35 of the outer tube extends downwards to reduce ingress of foreign matter into the clearance between inner and outer tubes.

The telescoping steady 31 is substantially the same as the steady 29, the two steadies serving as guiding means to maintain the cradle and base parallel during extension and retraction of jacking device.

A hydraulic jack 43 has a center line 44 coincident with a vertical axis of symmetry of the lifting device, and has a downwardly extending jack ram 45, the pair of parallel steadies thus straddling the jack. An upper end 46 of a cylinder of the jack is hinged by a bolt 49 to brackets 47 and 48 secured to the cradle 26. The ram 45 is similarly hinged by a bolt 54 at a lower end 50 to brackets 52 and 53. Hinge mounting above is a means of reducing bending loads applied to the cylinder and ram. The jack is mounted with the ram extending downwards to reduce chances of foreign matter being taken into the cylinder by the ram.

The jack 43 has a stroke less than the overlap 41, a stroke of the order of 6 inches has been found satisfactory. The device in FIG. 3 is shown in a retracted position, in which position the overlap 41 would be a maximum. In a fully extended position, (not shown) which is attained when the camper unit has been lifted off the bed of the truck, the over lap is less, being sufficient to maintain substantial alignment of the inner and outer tubes. The cradle and base have lengths 57 of the order of about 3 feet, and in the retracted position the lifting device has a height 53 of about 3 feet also, being less than the height of the lower corner edges of the camper unit above the ground when the truck is on reasonably flat ground.

With reference to FIG. 4, the lower corner edge 13 of the camper unit (shown in broken outline) is carried in the cradle 26 as shown, being a means to engage a portion of the camper unit for lifting. The inner tube 37 of a telescoping steady 29 has an out-rigger brace 55 secured at the lower end 39, a triangular strengthening gusset 56 extending between the tube 37 and the brace 55. The brace 55 has an outer end 58 having a means for height adjustment 60, being a bolt 61 threaded in a member 62. a head 63 of the bolt resting on level ground 65, shown as a line, in a first relative position.

In the first relative position of the ground and the jacking devices, a non-operative position, the head 63 of the bolt is retracted to a first position, that is the head of the bolt is adjacent the brace 58 so that the brace is substantially parallel with the ground 65, and the device 17 is at a first angle 67 to the ground, which angle is about 90. To bring the jacking device 17 into an operative position the bolt 61 is rotated such that the bolt head is extended downwards from the member 62 in a direction shown by an arrow 68 to a second position 63. Extension above rotates the brace 58 about the base 27 in the direction of the arrow 70, so

that the ground assumes a second position 65' (broken line) relative to the steady 29 such that the steady is canted at a second angle 67 to the ground. The angle 67 is about one hundred degrees thus in a front elevation (FIG. 2), the jacking device is canted inwards to the truck at an angle of about 10 to the vertical.

The out-rigger brace 55 and height adjustment means 60 serve as a means to cant the jacking device at a small angle to the vertical, to increase stability, as will be described with reference to FIG. 6. The steady 31 has a similar means 64 for height adjustment and is not described. If desired, each jacking device can have one out-rigger brace only (not shown) this can extend from one of the brackets 52 or 53.

FIG. 5

The hydraulic unit 20 includes a tank 76 for hydraulic fluid connected to a pump 77, which pump is a standard reciprocating hand pump. A hose 78 connects the pump to a hydraulic equalizer unit 80 which, through the hoses l8 and 19, communicates with the cylinders 43 of the lifting device. A manually operable valve 82 is in parallel with the pump 77, the valve being closed when the pump is operating, the valve serving as a means of draining the cylinders when the camper unit is to be lowered. The equalizer unit is a means to ensure that there is an equal volume flow to each cylinder 43 so that the cylinders are extended equally, ensuring that each side of the camper unit is raised in substantially equal increments, reducing a tendency of the camper unit to topple. A suitable equalizer is manufactured by the Pesco Products Company of Cleveland, Ohio, U.S.A., having a part number 10-397D. Thus, the hydraulic unit is a means of supplying equal volume flows of hydraulic fluid to the jacks of each jacking device. FIG. 6

The camper unit 10 is shown diagrammatically supported solely on two jacking devices in first and second positions 83 and 84, as seen in front elevation, the truck being omitted. In the first position 83 the jacking devices 17 are substantially parallel and at the angle 67 (about to level ground, i.e., the jacking devices are substantially parallel. In the second position 84, the devices 17 are both canted inwards at angle 89 to the vertical (about 10) by extending the bolts 61 of the means for height adjustment 60.

If a sideways force 87 is applied to the camper unit in the first position 83, little correcting force is available and thus, if the force 87 is sufficiently large, the camper unit would topple as shown by an arrow 90. This is therefore a generally unstable system, similar to that of prior art camper lifters.

If the sideways force 87 is applied to the camper unit in the second position 84, a correcting force tends to be generated by the weight of the camper as the center of gravity of the camper is raised slightly when one of the devices 17 tends to move to a vertical position. Thus the second position is a more stable position than the first position and tendency of the camper to topple is reduced.

OPERATION To remove a camper unit from a truck, the truck is parked on generally flat and level ground. The jacking devices are placed on either side of the truck, with the hydraulic jack generally vertically below the balance point of the camper unit, as seen in FIG. 1.

The cradle of the jacking devices engage the lower corner edges of the camper unit, as seen in FIG. 4, and the support means contact the ground. When fitting the jacking devices to each side of the camper unit, sometimes small adjustments of the hydraulic jack are made, to make the height of the jacking device slightly greater than the height of the comer edges 13 and 14, thus tilting the jacking devices. The bolt 61 is extended until the head 63 contacts the ground when the jacking device is inclined at a small angle, about to the vertical as seen in FIGS. 2 and 4. Generally speaking, when using the same camper/truck combination, once the height adjusting means 60 has been adjusted for a particular piece of ground, further adjustment is usually unnecessary.

An additional valve may be provided in each hose 18 and 19 (not shown) so that individual adjustment of the height of each jacking device is possible, thus compensating for slight variations in levelness of the ground. Care is taken to ensure that the lower comer edges of the camper unit nestle snugly along the complete length of the cradles and that full lengths of the bases are supported on the ground. The heads of the bolts of the height adjustment means are in contact with the ground and if excessive penetration of the bolt head into the ground occurs, a load supporting plate (not shown) is provided, as is well known in the art.

The lifting device is now ready for operation. The pump 77 is started, the valve 82 being closed. Equal volumes of hydraulic fluid leave the equalizer and are fed into each cylinder of the jacking devices. Extension of the jacks is continued until the camper unit is lifted clear of the truck, possibly 2 or 3 inches, care being taken to ensure that unbalancing or toppling due to lack of alignment does not occur. The truck is then moved away from under the camper unit and substitute supports are placed under the camper unit, for example, two saw-horses (not shown). The valve 82 is then opened and the weight of the camper unit forces fluid from the cylinders back into the tank 76, lowering the camper unit evenly onto the saw horses.

To load the camper unit onto the back of the truck, the reverse procedure is followed.

It is to be noted that an excessively large cant angle is likely to result in slippage occuring between the base and the ground, causing the camper unit to topple. For this reason the cant angle is limited to a maximum of about 20, which angle depends on the levelness of the ground, surface characteristics of the ground and other factors.

[claim 1. A jacking device 17 adapted to be used in conjunction with a plurality of jacking devices and a hydraulic unit 20, to be used as a camper unit lifting device for lifting a camper unit 10 on and off a bed 11 of a truck 12, each jacking device including:

a. extensible and retractable means having a longitudinal axis,

b. engaging means extending perpendicularly from the axis of the extensible and retractable means to engage the camper unit,

c. support means extending perpendicularly from the axis of the extensible and retractable means to support the jacking device on the ground,

d. guiding means to maintain the engaging means and the support means parallel during operation of the extensible and retractable means,

e. canting means adjacent the support means to cant the jacking devices inwards at a desired angle to the vertical before the jacking device carries weight of the camper unit, thus increasing stability of the camper unit mounted on the jacking devices.

2. Structure as defined in claim 1 in which the extensible and retractable means includes:

f. a hydraulic jack 43 extending between the engaging means and the support means.

3. Structure as defined in claim 1 in which the engaging means includes:

g. a cradle 26 adapted to engage a lower corner edge 13 of the camper unit.

4. Structure as defined in claim 1 in which the support means includes:

h. a base 27 substantially parallel to the engaging means adapted to lie on the ground and resist sinking into the ground.

5. Structure as defined in claim 1 in which the guiding means includes:

i. a pair of telescoping steadies 29, 31 straddling the extensible and retractable means, the steadies extending between the base and the cradle.

6. Structure as defined in claim 1 in which the canting means includes:

j. an out-rigger brace 55 extending outwards from the support means, the brace contacting the ground so as to tilt the jacking device at a cant angle 67 to the vertical.

7. Structure as defined in claim 6 in which the outrigger brace has:

k. means 64 to adjust height of an outer end 58 of the brace so as to vary the cant angle of the jacking device.

8. Structure as defined in claim 5, in which the telescoping steadies include:

i. an outer tube 33 having a bore and being secured at an upper end 34 to the engaging means,

m. an inner tube 37 secured at a lower end 39 to the support means,

clearance between the inner tube and the bore of the outer tube being such that the two tubes are maintained substantially aligned with each other and are free to slide axially relative to each other.

9. Structure as defined in claim 2 in which the hydraulic jack has an upper end 46 secured to the engaging means and a lower end 51 secured to the support means, the upper and lower ends being secured by: n. hinge means to reduce bending loads applied to cylinder and ram of the jack.

10. Structure as defined in claim 9 in which the hinge means includes:

o. hinge mounting of the upper end 46 of the jack to brackets 47 and 48, and hinge mounting of the lower end 51 of the ram 45 to brackets 52 and 53 secured to the base.

11. Structure as defined in claim 1 in which the hydraulic unit includes:

p. a tank 76 for hydraulic fluid,

q. a pump 77 for pumping fluid from the tank,

r. an equalizer unit 80 connected to the pump 77 with a hose 78, a valve 82 in parallel with the pump 77 to permit retraction of the hydraulic jacks, the equalizer unit being connected through hoses 18,19 to the cylinders 43 of the hydraulic jacks of the jacking devices. 

1. A jacking device 17 adapted to be used in conjunction with a plurality of jacking devices and a hydraulic unit 20, to be used as a camper unit lifting device for lifting a camper unit 10 on and off a bed 11 of a truck 12, each jacking device including: a. extensible and retractable means having a longitudinal axis, b. engaging means extending perpendicularly from the axis of the extensible and retractable means to engage the camper unit, c. support means extending perpendicularly from the axis of the extensible and retractable means to support the jacking device on the ground, d. guiding means to maintain the engaging means and the support means parallel during operation of the extensible and retractable means, e. canting means adjacent the support means to cant the jacking devices inwards at a desired angle to the vertical before the jacking device carries weight of the camper unit, thus increasing stability of the camper unit mounted on the jacking devices.
 2. Structure as defined in claim 1 in which the extensible and retractable means includes: f. a hydraulic jack 43 extending between the engaging means and the support means.
 3. Structure as defined in claim 1 in which the engaging means includes: g. a cradle 26 adapted to engage a lower corner edge 13 of the camper unit.
 4. Structure as defined in claim 1 in which the support means includes: h. a base 27 substantially parallel to the engaging means adapted to lie on the ground and resist sinking into the ground.
 5. Structure as defined in claim 1 in which the guiding means includes: i. a pair of telescoping steadies 29, 31 straddling the extensible and retractable means, the steadies extending between the base and the cradle.
 6. Structure as defined in claim 1 in which the canting means includes: j. an out-rigger brace 55 extending outwards from the support means, the brace contacting the ground so as to tilt the jacking device at a cant angle 67'' to the vertical.
 7. Structure as defined in claim 6 in which the out-rigger brace has: k. means 64 to adjust height of an outer end 58 of the brace so as to vary the cant angle of the jacking device.
 8. Structure as defined in claim 5, in which the telescoping steadies include: l. an outer tube 33 having a bore and being secured at an upper end 34 to the engaging means, m. an inner tube 37 secured at a lower end 39 to the support means, clearance between the inner tube and the bore of the outer tube being such that the two tubes are maintained substantially aligned with each other and are free to slide axially relative to each other.
 9. Structure as defined in claim 2 in which the hydraulic jack has an upper end 46 secured to the engaging means and a lower end 51 secured to the support means, the upper and lower ends being secured by: n. hinge means to reduce bending loads applied to cylinder and ram of the jack.
 10. Structure as defined in claim 9 in which the hinge means includes: o. hinge mounting of the upper end 46 of the jack to brackets 47 and 48, and hinge mounting of the lower end 51 of the ram 45 to brackets 52 and 53 secured to the base.
 11. Structure as defined in claim 1 in which the hydraulic unit includes: p. a tAnk 76 for hydraulic fluid, q. a pump 77 for pumping fluid from the tank, r. an equalizer unit 80 connected to the pump 77 with a hose 78, a valve 82 in parallel with the pump 77 to permit retraction of the hydraulic jacks, the equalizer unit being connected through hoses 18,19 to the cylinders 43 of the hydraulic jacks of the jacking devices. 